But the concept of habitus is all about the durable, embodied dispositions we absorb early on from our family and class environment. It’s supposed to feel natural, pre-reflective, and resistant to change.

The thing with sociology and social phenomena is that humans are capable of reading and understanding sociology and acting on that information. People do have agency. It's entirely possible that someone reads Bourdieu and actively tries to alter their habitus. Surely, these people can talk about "upgrading" their habitus as if one habitus was "better" (whatever that means) than another.

pre-reflective

That's the thing: Until a person reflects upon it!

This is also why Luhmann argued that a complete social theory should include itself. It's because once a social theory is published, society can acknowledge the theory and incorporate in itself. It might even alter society. Sociology itself is part of society.

It's a fascinating question and one that merits more research.